Getting Started

Umbra runs on the Flare Coston2 testnet. Nothing here uses real funds.

1. Connect a wallet

Open the app and click Connect Wallet. Umbra supports MetaMask, Coinbase Wallet, Rabby, Trust, Phantom, and anything reachable over WalletConnect.

Make sure your wallet is on Flare Coston2 (chain ID 114). The app talks to Coston2 through flare-testnet.drpc.org rather than the official coston2-api.flare.network endpoint, because the official RPC caps eth_getLogs at a 30-block range — which breaks the note wallet’s history scan outright.

2. Derive your note keys

The first time you use a shielded feature, your wallet asks you to sign a fixed message:

Umbra Shielded Wallet

Sign to derive your private note keys. This signature never leaves your device
and does not authorize any transaction.

That signature is the seed for your spending key — the single private value that owns every note in your wallet. Two things matter about it:

• It is not a transaction. Signing authorizes nothing on its own.
• It is deterministic. The same wallet always regenerates the same keys, so there is no separate seed phrase to back up. Your wallet is the backup.

The spending key never leaves your browser. Only the derived ownerKey — Poseidon2(spendingKey, 0) — is ever published. See Shielded Notes for why publishing it is safe.

3. Get testnet tokens

Head to the Faucet page. Umbra supports three assets on Coston2:

These are real Coston2 assets issued by Flare’s own faucet — FXRP comes from the actual FAssets bridge, not a simulated mint. The faucet page deep-links you to Flare’s faucet and watches your balance, notifying you the moment tokens land.

4. Shield your first deposit

Go to Shield, pick an asset and an amount, and confirm. Your browser computes a commitment to a new note and the vault inserts it as a Merkle tree leaf.

This step is a public ERC-20 transfer (or a native C2FLR send). Everyone can see you deposited. What nobody can see is which shielded note is yours afterwards — that link is what the rest of the protocol protects.

No zero-knowledge proof is needed here. You’re publishing a commitment, not spending one.

5. Do something private

With a shielded balance you can:

• Swap — place a dark pool order. Amount and assets stay private.
• Pay — send a shielded note to another registered user.
• Receive — register your ownerKey so others can pay you.
• Withdraw — exit publicly to any address.

Where your notes live

Your notes are stored in IndexedDB in your browser, and rebuilt by scanning the chain’s full event history from the vault’s deploy block. Two consequences:

• Clearing site data drops the local cache, but the notes are recoverable — the scan reconstructs them from chain history using your derived keys.
• The first scan on a new device takes a moment. It walks every vault event since block 33478628.